The objective of this research is to isolate antineoplastic substances from a group of marine organisms which have been confirmed by the National Cancer Institute as active potential sources of antitumor substances in PS (lymphocytic leukemia) or KB (cell culture of human nasopharynx carcinoma) test systems. Isolation will be guided by activity testing provided by the National Cancer Institute. Structures of pure active compounds incidentally obtained in the course of isolating the active antitumor agents will be investigated to the extent possible.